Battery help for boondocking

Discussion in 'Boondocking' started by ltdave, Jan 18, 2019.

  1. ltdave

    ltdave New Member

    Jan 18, 2019
    Hi Everyone,
    I'm new to the forum so I hope you'll bear with me. My wife and I have a 2001 Coleman/Fleetwood Sante Fe pop up. We do 97+ percent of our camping without electrical hookup. I would like to modify the popup and add a 12V cigarette recepticle to make it easier to use my BiPap machine. Should I try to splice into existing 12V wire or wire the cigarette recepticle back to the panel? I'm a complete novice when it comes to electrical/12V wiring. I think by upgrading my battery from a group 27 deep cycle to two 6V golf cart batteries that will help tremendously with added draw of BiPap. I need your help on all of it. Thanks in advance. We would like to take some longer trips this summer so I'll need to do my mods sooner rather than later.
  2. SteveP

    SteveP Well-Known Member

    May 21, 2015
    I tried tapping into an existing wire but it my cpap didn't run consistently, probably due the smaller gauge wires. You can tap into an existing circuit but try to choose one that's not used that much. I tapped the circuit for the 12 volt feed to the fridge as close to the panel as I could and ran 12 gauge AWG to the plug in and back to the 12 volt ground buss and no more issues other than keeping the battery charged.
  3. ltdave

    ltdave New Member

    Jan 18, 2019
    Thanks Steve. "back to the 12 volt ground buss" I'm really ignorant about wiring, can you elaborate
  4. Mogimus

    Mogimus Active Member

    Apr 29, 2015
    Rancho Cucamonga, CA
    When adding a plug for our CPAP, I ran a new heavier gauge line to the inverter and on its own fuse. Didnt want to tap into a light gauge wire and potentially causing other issues. Going with dual GC2 batteries would be a choice but anything longer than a weekend trip and you might want to think about how to recharge the batteries (IE solar, genny, eyc)
  5. PopUpSteve

    PopUpSteve Administrator

    Dec 22, 2002
    Malvern, PA
    I would go directly to the fuse panel or battery. I put in a combo 12v recepticle and USB by tapping the radio power but sometimes I don't get enough power. So one of my Spring projects is to rewire it and go direct to the main power.
  6. ltdave

    ltdave New Member

    Jan 18, 2019
    Thanks Mogaimus, Is there open spots on the inverter to hook the wire to? Sorry but I no nothing about wirings/inverters, etc
  7. Mogimus

    Mogimus Active Member

    Apr 29, 2015
    Rancho Cucamonga, CA
    I have a 2006 Fleetwood so it might be a little different but if you open up the front cover (on mine) on the left side you see house style breakers (120V) and on the right side you see 12V automotive style fuses. There was about half the spots open on that 12V side that I just ran a 12 gauge wire to one of the open ports and added an appropriate sized fuse... but you should do this with the camper not plugged into shore power and with the battery disconnected.
    PointyCamper and ltdave like this.
  8. ltdave

    ltdave New Member

    Jan 18, 2019
    Thanks that helps!!
  9. joet

    joet Well-Known Member

    Mar 16, 2011
    Elkins WV area
    I would run a dedicated, fused circuit from the battery. The problem with coming through the convertor is that there are other things hooked to the battery line that can and will cause a voltage drop.
  10. MNTCamper

    MNTCamper Active Member

    Jun 14, 2014
    There is no need to run straight to the battery. You aren't going to get any appreciable voltage drop fusing to the converter - that is what it is made for. The device in question is not a high amp draw device. If it was, it would only run for a few hours on the battery anyway. The converter is meant to be used as the fuse box for the camper.
  11. BillyMc

    BillyMc Active Member

    Mar 25, 2018
    South Carolina
    Does the machine run on 12v DC or does it require an inverter? We also don't know what the amp rating on your converter is. I personally would run a dedicated circuit directly to the battery and fuse it at the battery according to load and equipment. Fuse the circuit based on the weakest link.
  12. PaThacker

    PaThacker Well-Known Member

    Feb 11, 2010
    When I installed the fantastic fan on my non-powered vent opening I tapped directly into overhead lighting power lines. The fan had its own fuse. C- pap machine is different. I’d just run dedicated hi amp rated wire to the convertor for c-pap. While at it do cell phone and tablet low amp lines, and other accessories where able
    I do not have too many locations to run lines due to slideout, fridge and heater on street side and couch on curb side. Only spot for easy wiring is next to convertor mounted on rear wall.
  13. davido

    davido Active Member

    Jul 17, 2014
    What is the power draw of the cpap machine? How many amps does it draw at 12v?
    MyName likes this.
  14. MyName

    MyName Active Member

    Jan 12, 2018
    Check your Power Converter if you want to wire to it. Mine stated that it doesn't run "True" DC. I wasn't sure how my phones and tablets would like that. Also my camper has old 14 gauge wire. I connected straight to the battery with 12 gauge. I installed this and a few other things. If your BiPap machine runs on DC see about buying a DC plug for it. That way you don't need to go DC -> AC -> DC and will reduce your power lose. I also cleaned all of my rusty ground connections and I feel like my external running lights became brighter.

    I think I started a thread about my wiring project, I just don't know how to find it now. It had lots of pictures and cheesy wiring diagrams.
    Edit: Found the thread.
    Edit: corrected inverter to Power Converter
    Last edited: Jan 28, 2019
  15. dbhost

    dbhost Active Member

    Sep 19, 2018
    League City, Texas USA.
    FWIW, and not an answer per se to your answer, but I run my Resmed CPAP, with the humidifier turned off, off of one of those 1100 max amps jump starter boxes. Mine won't do 12v so I either do 110v AC or 24V DC, not a great set of options.... Anyway, I charge for about an hour and a half or so using my Harbor Freight TailGator generator (after everyone is up, and the campground kids are running around and screaming. I am typically the last to fire up my generator). IF your too worried about wiring in a 12V DC outlet, or your BiPAP requires 24V if doing DC, it is well worth looking into this method.
  16. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

    Jul 18, 2013
    Thornville, OH
    First thing you need to know is who many watts you will be using with the converted outlet. You need to figure our how many amps at 12V will need to supply the converter. so you know what size wire and fuse you need.

    Once you figure out the watts, convert to the amps you need at the 12V output to the converter. If it watts, its more simple (watts = volts X amps) so 120w will need about 10 amps. If it amps, convert to watts, (watts = volts X amps)- volts/ohms), so your 1o amp output at 120V ac is equal to 120v x 10A = 120W. I would then add 10% to the amps for the inefficiency of the converter. So your 10A is now 11 amps. so with 11 amps you need a #14 wire and 15 A fuse. Just for reference most common wire rating (#14 = 15 A, #12 = 20A, #10 = 30A)

    Amps used above is the rating of apme per hour. Batteries are rated in amp/hours at a certain amp draw, or amps per minutes at a certain draw. Only plan to use up to 50% of those amps available in the battery.

    Battery: I would skip the 27-G and go to 31-G, more amps available.

    Before you change batteries, you need figure out about how much amps you used. I know for us we need 2 - G-31 batteries for fall camping running the furnace for 4+ nights.

    But when figuring out your battery, you should not plan on using more than 50% of the rating. I use 12.0V as my lower limit. Anything greater than 50% will do long term harm to the battery (less available amps in the future and shorten it's life)
    Last edited: Jan 29, 2019
  17. bob414

    bob414 New Member

    Jan 31, 2019
    That would vary on what setting you are using. My power bricks for my RESMED say 90 Watts. That a little under 8 Amps @ 12 VDC, that is with humidity control and heating the water pot. I turn would turn that off boondocking.


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